Heat exchangers, more particularly for an air-heating device

ABSTRACT

The invention relates to a heat exchanger, more particularly for an air-heating device, which is mainly formed by two reversed Ushaped bent sheet metal wall parts, the upper portions of which are flat and lie at a relatively small distance from one another and are provided with one or more apertures with opposite upstanding peripheral walls along the rims of which they are interconnected, while the two portions extending downwardly at the front of the device enclose a combustion space and the two wall portions extending downwardly at the rear enclose a space connected to the flue gas outlet with a downdraft diverter.

United States Patent [111 3,604,505

[72] Inventor Arnold Van der Goot FOREIGN PATENTS Voorbroek, Netherlan 850,852 /1960 Great Britain 126/1 l0 [21] Appl. No. 814,403 Filed p 8, 1969 Primary Examiner-Frederick L. Matteson Assistant ExaminerThcophil W. Streule t t. 14 1971 Pate ed Sep Attorney-Holman & Stern [7 1 Assignee M taa ya e abrl ialyhelmlismailfi Terborg, Netherlands [54] HEAT EXCHANGERS, MORE PARTICULARLY FOR AN AIR-HEATING DEVICE 3Cl' ,2Dawin Fis.

alms r g g ABSTRACT: The invention relates to a heat exchanger, more [52] LS. Cl 165/131, tic la l fo an air-heating device which is mainly formed 126/91 by two reversed U-shaped bent sheet metal wall parts, the

[51] Int-Cl Fzsf 3/02 upper portions of which are flat and lie at a relatively small Field of Search 126/ l 10 A, distance f one another and are provided with one or more 91, 1 10; 165/131, 164 apertures with opposite upstanding peripheral walls along the rims of which they are interconnected, while the two portions [56] References C'ted extending downwardly at the front of the device enclose a UNITED STATES PATENTS combustion space and the two wall portions extending 2,792,826 5/1957 Kilbury 126/1 10 downwardly at the rear enclose a space connected to the flue 2,9769 l 7 3/1961 Wyckoff et al. 126/110 gas outlet with a downdraft diverter.

PATENTED SEP] 4191:

v I I FIG.1

HEAT EXCHANGERS, MORE PARTICULARLY FOR AN AIR-HEATING DEVICE Various forms of a device'are already known, and a typical such heat exchanger consists of stretched, deflected, smooth sheet iron and is therefore composed of several parts provided with connecting flanges along which they are interconnected, e.g. by welding. Such a construction is expensive and laborious, while it also requires special attention in view of stresses remaining in the material, which can cause warping and deformations of the whole construction. The walls of the heat exchanger are smooth and ribbed by the deformation. Additionally, the parts are interconnected to an uninterrupted body which causes clicking noises when the temperature of the device increases or decreases, due to thermal expansion and contraction.

The invention aims at providing a very favorable device by means of which the above drawbacks are overcome at least to a high degree.

According to the invention this object is accomplished by providing a heat exchanger wherein the two U-shaped bent sheet metal wall parts forming the inner and outer wall parts thereof, each comprise a continuous piece of sheet material, corrugated or ribbed in transverse direction, of which the slanting corrugation portions make an angle of about 3060 with respect of the main plane to the wall parts concerned and which wall parts are tightly interconnected along the side rims, and the corrugated or ribbed sheet metal wall parts in the upper portion being only interconnected along the flanges flanged inwardly from the opposite upstanding walls of the apertures. In this manner a heat exchanger is obtained which is considerably simpler to manufacture, and in which the heatexchanging area is considerably larger than with a known device with smooth walls, so that an increased efficiency of the heat transfer can be obtained without requiring that the overall dimensions become correspondingly greater.

It has been proved that it is possible, without introducing drawbacks, to bend the above-described corrugated or ribbed material to an arcuate form, of which the corrugation tops and dales or the ribs run from an end of one of the U-legs to the end of the other Uleg, by means of bends to the direction of the corrugation tops and dales. In this way, on one hand, a good contact is obtained between the passing flue gases and the exchanger walls, and on the other hand, between these walls and the ambient air, so that a particularly favorable heat exchange takes place. A further advantage of the invention is that the two U-shaped corrugated or ribbed sheet metal wall parts can each be made in one piece whereby difficulties in the fitting together and additional stresses can be avoided to a high degree, while also in the manufacture the making of connections between portions of the walls can be avoided without thereby causing the presence of clicking noises due to temperature rises and falls. Furthermore a good tight and immovable fast connection of the upstanding walls of the apertures in the upper portion can be obtained in a particularly simple and favorable manner, which connection on the other hand, as a consequence of the nature of the sheet material used, is also still sufficiently resilient at that place so that during warming up and cooling down no stresses arise which can give rise to clicking noises. The whole is therefore completely or practically completely, noiseless.

Advantageously the fixation of the flanges of the upstanding walls of the apertures in the upper portions is accomplished by folding back the horizontal flange of one of the opposite upstanding walls around the flange of the other wall.

Preferably, finally, the two U-shaped corrugated or ribbed wall parts of the heat exchanger are laterally closed by flat welded end walls of sheet metal. This is most advantageous in manufacture and is probably also most favorable in practice.

The invention will now be further elucidated with reference to an example of performance shown in the accompanying drawing. In the drawing:

FIG. 1 shows a cross section according to the plane I-I in FIG. 2 of a heat exchanger according to the invention, and

FIG. 2 shows a side elevational view, partially in section, according to the plane II-II in FIG. 1. I

In the drawing, 1 is a heat source which may comprise, for example an oil burner or a fire pot of a coalfurnace or a gas burner. This heat source is arranged under the inlet opening of a substantially U-shaped heat exchanger which is substantially formed by two U-shaped bent sheet metal wall members 2 and 3 of corrugated sheet material, of which the corrugated portions of the wall make an angle of about 45 with respect to the main plane of the sheet metal wall member, or of ribbed sheet material. The corrugated sheet material may be either zigzag or arcuate corrugated material. The U-shaped wall member forming the outer walls 2, 4 and 8 of the heat exchanger is bent to a substantially rectangular U shape while the member forming the inner walls 3, 5 and 6 has converging leg portions 3 and 6, of which one inner wall 3 extends downwardly substantially the same distance as the long outer leg 2, while the other inner wall 6 is a little wall 6 is a little shorter and is slightly bent out again at some distance from the bottom end, namely at substantially the level of the outlet stud 16 for the flue gases in the outer rear wall portion 8, so that the bottom portion 7 runs substantially parallel to the opposite inner wall portion 3. The two bottom rear wall portions 7 and 8 end at substantially the same level at 9. In the middle the two rear wall portions 7 and 8 are further provided with a recess 18 through which, with positive draft, the air can stream directly into the outlet stud 16. A stationary downwardly slanting guide baffle 15 is further connected to the rear wall 8 at 17, over the outlet stud 16. In the upper portion the two intermediate portions 4 and 5 of each of the U-shaped inner and outer wall parts each forming a single piece, lie horizontal and parallel and are provided with vertical apertures 12. These apertures are defined all around by upstanding walls 10 and 11 with flanges 20, 20a directed inwardly and formed on the two U-shaped sheet metal wall portions 4 and 5 by deformation and punching out and fitting against one another. The connection is closed in these apertures inasmuch as one of the flanges 20a is broader than, the opposite one (20) and is bent back round this latter as is shown in FIG. 2.

Along the lateral end rims the two sheet metal parts 2, 4, 8, and 3, '5, 6, 7 are interconnected and closed by means of smooth sideplates 14 arranged and welded along the rims 13 thereof.

In practice, the shown heat exchange may be appropriately built into a housing so that an air-heating device is obtained.

In the drawing the solid arrows 30 indicate the stream directions of the flue gases from the burner 1 to the outlet stud 16 for the flue gases and the dotted arrows 31 indicate the stream directions of the ambient air at the outside of the heat exchanger portions. The drawing shows a preferred embodiment in which the exchanger is open at the rear at 9 for diverting or leading off downdraft it it appears, and the arrows 32 indicated in dots and dashes indicate the airflow in such a case, but the construction may be different at this place and e.g. it may be closed at 9. The possibility of the appearance of clicking noises, however, will then be greater. The shown construction has proved completely or practically completely free of such clicking noise.

I claim:

1. A heat exchanger, particularly for an air-heating device, comprising an inner U-shaped wall member and an outer U- shaped wall member spaced therefrom, each of said wall members comprising a generally horizontal intermediate transverse portion, a front portion extending downwardly from one end of said transverse portion and joined thereto along a first bend line, and a rear portion extending downwardly from the opposite end of said transverse portion and joined thereto along a second bend line generally parallel to said first bend line, said inner and outer wall members each comprising a single continuous sheet of corrugated metal having corrugations extending continuously longitudinal along said front and rear portions and said transverse portions perpendicular to said bend lines, said wall members defining therebetween a generally U-shaped chamber; first and second secured to the opposite sides of said inner and outer wall members around the periphery thereof.

3. A heat exchanger as defined in claim 1, wherein at least one of said first and second flange means includes a portion which is folded about the other of said flange means to thereby secure said first and second flange means together. 

1. A heat exchanger, particularly for an air-heating device, comprising an inner U-shaped wall member and an outer U-shaped wall member spaced therefrom, each of said wall members comprising a generally horizontal intermediate transverse portion, a front portion extending downwardly from one end of said transverse portion and joined thereto along a first bend line, and a rear portion extending downwardly from the opposite end of said transverse portion and joined thereto along a second bend line generally parallel to said first bend line, said inner and outer wall members each comprising a single continuous sheet of corrugated metal having corrugations extending continuously longitudinal along said front and rear portions and said transverse portions perpendicular to said bend lines, said wall members defining therebetween a generally U-shaped chamber; first and second upstanding peripheral flange means respectively secured to said transverse portions of said inner and outer wall members, said first and second peripheral flange means being secured at their free ends to each other and defining a heat exchange passage extending through the heat exchanger.
 2. A heat exchanger as defined in claim 1, further comprising a pair of oppositely disposed sideplates respectively secured to the opposite sides of said inner and outer wall members around the periphery thereof.
 3. A heat exchanger as defined in claim 1, wherein at least one of said first and second flange means includes a portion which is folded about the other of said flange means to thereby secure said first and second flange means together. 